Abstract. We introduce a methodology to visualise rapid vertical and zonal tropical
transport pathways. Using prescribed sea-surface temperatures in four monthly
model integrations for 2005, we characterise preferred transport routes from
the troposphere to the stratosphere in a high resolution climate model. Most
efficient transport is modelled over the Maritime Continent (MC) in November
and February, i.e., boreal winter. In these months, the ascending branch of
the Walker Circulation over the MC is formed in conjunction with strong deep
convection, allowing fast transport into the stratosphere. In the model the
upper tropospheric zonal winds associated with the Walker Circulation are
also greatest in these months in agreement with ERA-Interim reanalysis data.
We conclude that the Walker circulation plays an important role in the
seasonality of fast tropical transport from the lower and middle troposphere
to the upper troposphere and so impacts at the same time the potential supply
of surface emissions to the tropical tropopause layer (TTL) and subsequently
to the stratosphere.